Post-operative neck ultrasound and risk stratification in differentiated thyroid cancer patients with initial lymph node involvement

Abstract

Objective: Cervical ultrasound (US) scan is a key tool for detecting metastatic lymph nodes (N1) in patients with papillary thyroid cancer (PTC). N1-PTC patients are stratified as intermediate-risk and high-risk (HR) patients, according to the American Thyroid Association (ATA) and European Thyroid Association (ETA) respectively. The aim of this study was to assess the value of post-operative cervical US (POCUS) in local persistent disease (PD) diagnosis and in the reassessment of risk stratification in N1-PTC patients. Design: Retrospective cohort study. Methods: Between 1997 and 2010, 638 N1-PTC consecutive patients underwent a systematic POCUS. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of POCUS for the detection of PD were evaluated and a risk reassessment using cumulative incidence functions was carried out. Results: After a median follow-up of 41.6 months, local recurrence occurred in 138 patients (21.6%), of which 121 were considered to have PD. Sensitivity, specificity, NPV, and PPV of POCUS for the detection of the 121 PD were 82.6, 87.4 95.6, and 60.6% respectively. Cumulative incidence of recurrence at 5 years was estimated at 26% in ETA HR patients, 17% in ATA intermediate-risk patients, and 35% in ATA HR patients respectively. This risk fell to 9, 8, and 11% in the above three groups when the POCUS result was normal and to !6% when it was combined with thyroglobulin results at ablation. Conclusion: POCUS is useful for detecting PD in N1-PTC patients and for stratifying individual recurrence risk. Its high NPV could allow clinicians to tailor follow-up recommendations to individual needs.

Repeat Ultrasonography in the First Years after Therapy with Radioiodine Is Not Necessary in Most Patients with Papillary Thyroid Carcinoma when Postoperative Ultrasonography Is Negative: A Reduction of Costs and False-Positives

“…Easily available information was used to define “the absence of persistent disease” after thyroidectomy. In fact, RxWBS has always been recommended after RAI therapy [2] and postoperative US (before RAI) is currently also indicated [1-3, 6, 7]. Finally, we restricted follow-up to the first 5 years after treatment with RAI, since most recurrences occur during this period [1, 14, 15] and periodic US examination is more commonly recommended during these years [1, 3].…”

“…Recently, postoperative US (before RAI) has been shown to be a valuable procedure [1-3, 6, 7], which can even detect lymph node metastases not apparent on RxWBS [6-8]. So far, few studies have routinely obtained postoperative US before RAI in a large number of patients [6, 7].…”

“…The time to obtain US after surgery was also not predefined or standardized. Finally, only one study reported the results of US after RAI in patients with negative postoperative US [6]. …”

Persistent and recurrent disease in patients with papillary thyroid carcinoma with clinically apparent (cN1), but not extensive, lymph node involvement and without other factors for poor prognosis

“…Finally, Lepoutre-Loussey and cols. found ectopic uptake on RxWBS in 28/171 patients with stage N1 disease, Tg-ablation < 1 ng/mL, and negative postoperative US (39). However, the authors did not report how many of these patients had tumors > 4 cm, aggressive histology, and extensive extrathyroid invasion, nor did they describe the characteristics of the LNM (size, number, extranodal extension).…”

“…A possible poor prognosis related to the location of LNM in the lateral compartments (N1b) also seems to be minimized when US is negative (9)(10)(11)(12). Finally, the efficacy of initial LN dissection, based on the persistence or not of LNM after surgery (39), is an important prognostic factor. In this respect, the fact that we included only patients with apparently complete tumor resection and postoperative US negative for LNM may have contributed to the result found.…”